#include<iostream>
#include<vector>
#include<queue>
#include<cstring>
#include<cmath>
#include<map>
#include<set>
#include<cstdio>
#include<algorithm>
#define debug(a) cout<<#a<<"="<<a<<endl;
using namespace std;
const int maxn=3e5+1000;
typedef long long LL;
inline LL read(){LL x=0,f=1;char ch=getchar();	while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
return x*f;}
bool vis[maxn];
vector<LL>v;
int main(void){
   cin.tie(0);std::ios::sync_with_stdio(false);
   LL n,x;cin>>n>>x;
   vis[0]=true;
   v.push_back(0);
   for(LL i=1;i<(1<<n);i++){
       if(vis[i^x]) continue;
       v.push_back(i);
       vis[i]=true;
   }
   cout<<v.size()-1<<"\n";
   for(LL i=0;i<v.size()-1;i++){
       cout<<(v[i+1]^v[i])<<" ";
   }
   cout<<"\n";
   return 0;
}
